2017-03-04 20:43 GMT+02:00 Brian Potkin <claremont...@gmail.com>: > On Fri 03 Mar 2017 at 20:28:56 +0200, Martin-Éric Racine wrote: > >> 2017-03-03 18:25 GMT+02:00 Francesco Potortì <poto...@isti.cnr.it>: >> >> > This apparently has to do with the old problem of cups-pdf converting >> > PDF to PS and back to PDF. >> > >> > I have an old Ubuntu Lucid installation where the problem does not >> > exist. >> >> Debian and Ubuntu both briefly used a patch (around version 2.5.1 >> IIRC) that bypassed the pdf2pdf filter. It worked well for simply >> passing documents that were already in PDF format over to CUPS for >> output to a PDF spool. However, it completely broke CUPS-PDF's >> primary functionality which is to convert arbitrary document formats >> into PDF, and it also prevented users from further manipulating the >> documents via CUPS-PDF's configuration file options before outputting >> them to the PDF spool. This resulted in complaints from users who >> depended upon these features, so I removed the patch. > > The fullest discussion of this I know of is at > > https://bugs.launchpad.net/ubuntu/+source/cups-pdf/+bug/820820 > > Users should take note of the comment: > > > The reasons for not skipping this step are known to you > > (it will severly impede the functionality of CUPS-PDF). > > Furthermore, once again, CUPS-PDF is not meant for > > processing PDF-input (i.e., it is not meant to be a > > PDF-manipulation tool). > > However, cups-pdf is still seen as a general "convert something to a > PDF" utility. At one time it might have served that purpose, but not > now. Both text and PDF input produce a below-standard, non-searchable > output. There is a case for clarifying its purpose as a cups-filters > plus backend method for getting a decent quality, searchable PDF from > PostScript input only. (Okular produces PostScript; Evince doesn't).
As far as I can tell, the reason why the quality of the output has varied over time is because the quality of Ghostscript itself has varied a lot. There might be better filters than Ghostscript we could call to handle the generic document conversion step. However, that's entirely upstream's decision. Martin-Éric
